<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>06_外间距测试</title>
    <style>
        body{
            margin: 0;
        }

        *{
            margin: 0;
            padding: 0;
        }

    </style>
</head>
<body>

    <div class="fu">
        <div class="z1">子元素1</div>
        <div class="z2">子元素2</div>
        <div class="z3">子元素3</div>
        <div class="z4">子元素4</div>
    </div>

</body>
</html>